RMS power sensor with 84 dB dynamic range

Abstract

A power meter includes components to measure RMS power over an 84 dB range or greater using the I-V square-law relation of a diode for measurements. The power meter includes multiple diodes along with a power distribution manifold which includes power dividers to distribute an input signal to the diodes. In one embodiment, a first power divider ( 202 ) distributes power to a first one of the diodes ( 203 ), and to the second power divider ( 204 ) which distributes power to the second ( 210 ) and third ( 212 ) diodes. The first power divider ( 202 ) is connected without attenuation to the first diode ( 203 ). The second power divider ( 204 ) is connected to the second diode ( 210 ) through a 11 dB attenuator ( 206 ), and to the third diode ( 212 ) through a 28 dB attenuator ( 208 ). With such attenuation, the first diode can operate in its square law range for measurements of signals with power from −64 dBm to −14 dBm, while the second diode can operate in its square law range for signals with power from −14 dBm to +3 dBm, and the third diode can operate within its square law range for signals with power from +3 dBm to +20 dBm. By measuring the current from the appropriate diode depending on the power level of the input signal, RMS power can be determined accurately over an 84 dB operating range. In an alternative embodiment, unequal power dividers ( 402 ) and ( 404 ) are used to distribute power and eliminate the need for attenuators ( 206 ) and ( 208 ) and to provide greater operating range sensitivity.

What is claimed is:  
     
       1. A power sensor comprising: 
       diode detectors, each having an input, and having an output providing an output of the power sensor; and  
       a power distribution manifold having an input forming an input to the power sensor and at least three outputs, each one of the three outputs coupled to the input of a respective one of the diode detectors, the power distribution manifold for distributing a signal provided from the input of the power sensor to the diode detectors so that a different attenuation is provided between the power sensor input and each one of the diode detectors, the different attenuation values set so that a greater overlap of diode square law operation range occurs between a first two of the diode detectors which receive a signal from the power sensor input with a higher combined attenuation than a second two of the diode detectors.  
     
     
       2. The power sensor of claim  1 , wherein the diode detectors each comprise: 
       a resistor having a first terminal coupled to the input of the diode detector, and a second terminal  
       a diode having a first terminal coupled to the second terminal of the resistor, and having a second terminal coupled to the output of the diode detector; and  
       a capacitor coupling the second terminal of the diode to a ground connection.  
     
     
       3. The power sensor of claim  1 , further including a filter comprising: 
       a second resistor coupling the second terminal of the diode to the output of the diode detector; and  
       a capacitor coupling the output of the diode detector to a ground connection.  
     
     
       4. The power sensor of claim  1 , wherein the diode detectors each comprise: 
       a first resistor having a first terminal coupled to the input of the diode detector, and having a second terminal;  
       a first pn-diode having a p-terminal coupled to the second terminal of the first resistor, and having an n-terminal coupled to a + output of the diode detector;  
       a first capacitor coupling the n-terminal of the first pn-diode to a ground connection;  
       a second resistor having a first terminal coupled to the input of the diode detector, and having a second terminal;  
       a second pn-diode having an n-terminal coupled to the second terminal of the second resistor, and having a p-terminal coupled to a − output of the diode detector; and  
       a second capacitor coupling the p-terminal of the second pn-diode to a ground connection.  
     
     
       5. The power sensor of claim  4 , wherein the diode detectors each further comprise: 
       a third resistor coupling the n-terminal of the first pn-diode to the + output of the diode detector;  
       a third capacitor coupling the + output of the diode detector to a ground connection;  
       a fourth resistor coupling the p-terminal of the second pn-diode to the − output of the diode detector; and  
       a fourth capacitor coupling the − output of the diode detector to a ground connection.  
     
     
       6. The power sensor of claim  1 , wherein the power distribution manifold comprises: 
       at least one power divider connected to distribute power from the input of the power sensor to an input of each of the diode detectors.  
     
     
       7. The power meter of claim  6 , wherein the power distribution manifold further comprises at least one attenuator, each attenuator connecting a power divider output to the input of one of the diode detectors. 
     
     
       8. The power sensor of claim  6 , wherein the at least one power divider provides an unequal power division to enable the different attenuation to be provided between the power sensor input and each one of the diode detectors. 
     
     
       9. A power sensor comprising: 
       a power divider having an input forming an input to the power sensor, and having first and second outputs with an unequal power division provided between the input of the power divider and its first and second outputs;  
       a first resistor having a first terminal coupled to the first output of the power divider, and having a second terminal;  
       a first diode having a first terminal coupled to the second terminal of the first resistor, and having a second terminal coupled to a first output of the power sensor;  
       a first capacitor coupling the second terminal of the first diode to a ground connection;  
       a second resistor having a first terminal coupled to the second output of the power divider, and having a second terminal;  
       a second diode having a first terminal coupled to the second terminal of the second resistor, and having a second terminal coupled to a second output of the power sensor; and  
       a second capacitor coupling the second terminal of the second diode to a ground connection.  
     
     
       10. The power sensor of claim  9  further comprising: 
       a third resistor coupling the second terminal of the first diode to the first output of the power sensor;  
       a third capacitor coupling the first output of the power sensor to a ground connection;  
       a fourth resistor coupling the second terminal of the second diode to the second output of the power sensor; and  
       a fourth capacitor coupling the second output of the power sensor to a ground connection.  
     
     
       11. A power sensor comprising: 
       a first power divider having an input forming an input to the power sensor, and having first and second outputs with an unequal power division provided between the input and the first and second outputs;  
       a second power divider having an input coupled to the first input of the first power divider, and having first and second outputs with an unequal power division provided between the input of the second power divider and its first and second outputs;  
       a first resistor having a first terminal coupled to the second output of the first power divider, and having a second terminal;  
       a first diode having a first terminal coupled to the second terminal of the first resistor, and having a second terminal coupled to the first output of the power sensor;  
       a first capacitor coupling the second terminal of the first diode to a ground connection;  
       a second resistor having a first terminal coupled to the first output of the second power divider, and having a second terminal;  
       a second diode having a first terminal coupled to the second terminal of the second resistor, and having a second terminal coupled to the second output of the power sensor;  
       a second capacitor coupling the second terminal of the second diode to a ground connection;  
       a third resistor having a first terminal coupled to the second output of the second power divider, and having a second terminal;  
       a third diode having a first terminal coupled to the second terminal of the third resistor, and having a second terminal coupled to the third output of the power sensor; and  
       a third capacitor coupling the second terminal of the third diode to a ground connection.  
     
     
       12. The power sensor of claim  11  further comprising: 
       a fourth resistor coupling the second terminal of the first diode to the first output of the power sensor;  
       a fourth capacitor coupling the first output of the power sensor to a ground connection;  
       a fifth resistor coupling the second terminal of the second diode to the second output of the power sensor;  
       a fifth capacitor coupling the second output of the power sensor to a ground connection;  
       a sixth resistor coupling the second terminal of the third diode to the third output of the power sensor; and  
       a sixth capacitor coupling the third output of the power sensor to a ground connection.  
     
     
       13. A power sensor comprising: 
       diode detectors, each having an input, and having an output providing an output of the power sensor;  
       a power distribution manifold having an input forming an input to the power sensor and outputs coupled to the inputs of the diode detectors, the power distribution manifold for distributing a signal provided from the input of the power sensor to the diode detectors so that a different attenuation is provided between the power sensor input and each one of the diode detectors, wherein the power distribution manifold comprises at least one power divider connected to distribute power from the input of the power sensor to an input of each of the diode detectors, and wherein the at least one power divider provides an unequal power division to enable the different attenuation to be provided between the power sensor input and each one of the diode detectors.